A clay-based electrothermal composite membrane for directly capturing CO2 from air, preparation method and application thereof

Abstract

The present invention belongs to the field of carbon capture technology and discloses a clay-based electrothermal composite membrane for directly capturing CO2 from the air, a preparation method, and an application. The preparation method is as follows: S1, preparing a one-dimensional clay nanofiber dispersion; S2, preparing a high molecular polymer solution; S3, preparing a polyethyleneimine composite slurry; S4, heating-assisted evaporation film formation; the preparation method proposed in the present invention does not require chemical modification, the production process is simple and efficient, easy to scale up, and the production raw materials are cheap and readily available, and green and environmentally friendly. The prepared sepiolite-based composite membrane can directly capture low-concentration carbon dioxide from the air, has a high carbon dioxide adsorption capacity, and can utilize the excellent electrothermal properties of the adsorbent to achieve rapid adsorbent regeneration under DC voltage. The direct air capture carbon dioxide adsorbent of the present invention has the characteristics of high adsorption capacity, stable cycle, low cost, low regeneration cost, and scalable preparation, and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon capture, and relates to a clay-based electrothermal composite membrane for directly capturing CO2 in the air, a preparation method and an application thereof. Background Art

[0002] With the acceleration of industrialization and the growing severity of global climate change, reducing greenhouse gas emissions, particularly carbon dioxide (CO2), has become a major challenge facing the international community. Direct air capture (DAC) technology, as a potential solution, is expected to provide important support for achieving carbon neutrality by directly separating and capturing CO2 from the atmosphere. However, existing DAC technology still faces numerous challenges in terms of energy consumption, cost, and material stability.

[0003] Currently, direct air capture technologies primarily rely on liquid or solid adsorbents to capture CO2. However, these methods often suffer from limited adsorption capacity, difficulty in regeneration, and high energy consumption. Furthermore, while traditional adsorbents such as activated carbon and molecular sieves have some capture capacity, they are susceptible to humidity in practice and the regeneration process is energy-intensive, limiting their large-scale application.

[0004] Clay minerals, a class of silicate minerals with a unique layered structure, hold great promise for application in environmental remediation due to their excellent adsorption properties, ion exchange capacity, and stability. However, the application of single clay materials in direct air capture is limited by their low CO2 selectivity and adsorption capacity, as well as potential thermal stability issues during regeneration. Therefore, improving the CO2 capture performance and regeneration efficiency of clay-based materials through modification or composite methods has become an important research topic.

[0005] Currently, regeneration of solid-state amine adsorbents typically involves temperature swing adsorption (TSA), pressure swing adsorption (PSA), vacuum swing adsorption (VSA), or a combination of these methods. For direct air capture, Rahimi et al., in their bench-scale demonstration of CO₂ capture with an electrochemically driven proton concentration process, noted that PSA technology consumes significant energy for compressing non-target gases such as nitrogen and oxygen. In TSA technology, the heat input primarily acts on the solid and has no clear correlation with the CO₂ source concentration. Therefore, better methods are needed to reduce the energy consumption of adsorbent regeneration. In the pursuit of optimizing the performance of clay-based adsorbents, the introduction of carbon nanomaterials (such as carbon nanotubes and graphene) has endowed the materials with synergistic electrothermal and photothermal properties, significantly improving their regeneration efficiency and reducing energy consumption. Specifically, the high electrical conductivity and photothermal conversion capabilities of carbon nanomaterials enable the adsorbent to rapidly heat up through electrical heating or solar irradiation, thereby reducing the external energy input required for traditional thermal regeneration.

[0006] To address the shortcomings of existing technologies, this paper proposes a clay-based electrothermal composite membrane for direct air CO2 capture and its preparation method. This composite membrane combines the natural advantages of clay minerals with modern electrothermal technology. By optimizing material composition and structural design, it aims to achieve efficient and low-energy CO2 capture and adsorbent regeneration. Summary of the Invention

[0007] The present invention aims to provide an efficient, stable, and easily regenerated clay-based electrothermal composite membrane material and a simple and easy preparation method. This approach aims to offer a new material option and technical solution for direct air capture technology, thereby promoting the development and application of CO2 emission reduction technologies, which is of great significance for mitigating global climate change. The present invention also explores the influence of various factors on the performance of the composite membrane, providing a theoretical basis and practical guidance for further optimizing material properties.

[0008] The technical solution of the present invention:

[0009] A method for preparing a clay-based electrothermal composite membrane for directly capturing CO2 in the air comprises the following steps:

[0010] S1. Preparation of one-dimensional clay nanofiber dispersion:

[0011] The one-dimensional clay material is mixed with deionized water to prepare a mixed aqueous solution with a mass-volume concentration of 10 to 30 g / L to obtain a one-dimensional clay mixed solution; the one-dimensional clay mixed solution is subjected to ultrasonic dispersion treatment to obtain a one-dimensional clay nanofiber dispersion solution;

[0012] S2. Preparation of polymer solution:

[0013] The polymer was mixed with deionized water, and the mixture was heated in an oil bath at 70° C. and magnetically stirred at 500 rpm for 2 hours to completely dissolve the polymer in the deionized water to prepare a polymer solution with a mass-volume concentration of 10 to 50 g / L.

[0014] S3, preparing polyethyleneimine composite slurry:

[0015] The carbon nanomaterial is mixed with a one-dimensional clay nanofiber dispersion to prepare a carbon material and clay fiber mixed solution 1 having a mass-volume concentration of 15 to 50 g / L, and the mixed solution 1 is then subjected to ultrasonic dispersion treatment to uniformly disperse the carbon nanomaterial in the dispersion; a polymer solution is added to the mixed solution 1, and the mass of the polymer in the polymer solution is 5 to 15 wt% of the solid content in the mixed solution 1 of the carbon material and clay fiber to obtain a carbon material clay polymer mixed dispersion 2; a polyethyleneimine solution with a concentration of 100 g / L is added to the carbon material clay polymer mixed dispersion 2, and the polyethyleneimine in the polyethyleneimine solution is 10 to 50 wt% of the solid content in the carbon material clay polymer mixed dispersion 2; the carbon material clay polymer mixed dispersion 2 after the polyethyleneimine is added is magnetically stirred at a speed of 300 rpm for 10 minutes and subjected to bath ultrasonication for 10 minutes to obtain a uniformly mixed polyethyleneimine composite slurry;

[0016] S4, heating assisted evaporation film forming:

[0017] The polyethyleneimine composite slurry obtained in step S3 is assisted to evaporate at a temperature of 40° C. to 60° C. for 6 to 12 hours to obtain a clay-based electrothermal composite membrane for directly capturing CO 2 in the air.

[0018] The ultrasonic dispersion treatment is performed by using a tip ultrasonic treatment; in step S1, the ultrasonic treatment time is 30 to 60 minutes; in step S3, the ultrasonic treatment time is 10 to 30 minutes.

[0019] The one-dimensional clay material is sepiolite or palygorskite.

[0020] The carbon material is multi-walled carbon nanotubes, carbon black or graphite powder.

[0021] The polymer solution is a polyvinyl alcohol solution, a chitosan solution, a gelatin solution or a xanthan gum solution.

[0022] The beneficial effects of the present invention are as follows: the present invention significantly improves the adsorption capacity and selectivity of the composite membrane for CO2 by compounding one-dimensional clay nanofibers with polyethyleneimine (PEI); adopts an electrothermal assisted regeneration mechanism, and the composite membrane of the present invention can achieve rapid desorption and regeneration with low energy consumption; all raw materials used are non-toxic or low-toxic substances, and no harmful by-products are produced during the preparation process, which complies with the principles of green chemistry; in addition to CO2 capture, the composite membrane of the present invention also has certain antibacterial and anti-pollution properties, and can be applied to multiple fields such as air purification and water treatment, showing broad application prospects. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is further described below in conjunction with the technical solution.

[0024] The design concept of the present invention is as follows: Ultrasonic dispersion is used to uniformly disperse a high-specific-surface-area one-dimensional clay material in deionized water, providing the foundation for the subsequent composite membrane. A carbon nanomaterial is then mixed with a one-dimensional clay nanofiber dispersion and ultrasonically dispersed to evenly disperse the carbon nanomaterial. A polymer solution is then added, and the polymer content is adjusted to optimize the performance of the composite membrane. Finally, a polyethyleneimine solution is added to further enhance the composite membrane's CO2 adsorption capacity and stability.

[0025] The clay-based electrothermal composite membrane prepared by the present invention has the following characteristics: CO2 adsorption performance is 1.52-2.34 mmol / g, the thermal equilibrium temperature after applying a voltage of 30V at both ends of the composite membrane is 95-105°C, and the thermal equilibrium temperature under the irradiation of one sun is 82-90°C. The adsorbent can be regenerated and desorbed, and the regeneration energy consumption is reduced. After 5 regeneration cycles, the adsorption performance of the composite membrane does not change significantly.

[0026] In the following embodiments, the one-dimensional clay material is sepiolite as an example, but not limited thereto; the carbon nanomaterial is multi-walled carbon nanotube as an example, but not limited thereto; and the polymer solution is polyvinyl alcohol solution as an example, but not limited thereto.

[0027] Example 1:

[0028] A method for preparing a clay-based electrothermal composite membrane for directly capturing CO2 in the air comprises the following steps:

[0029] S1. Preparation of sepiolite nanofiber dispersion:

[0030] Mixing sepiolite with deionized water to prepare a mixed aqueous solution with a mass-volume concentration of 10 g / L to obtain a one-dimensional clay mixed solution; subjecting the one-dimensional clay mixed solution to ultrasonic dispersion treatment to obtain a one-dimensional clay nanofiber dispersion;

[0031] S2, preparing polyvinyl alcohol solution, comprising the following steps:

[0032] The high molecular weight polymer was mixed with deionized water, and the mixture was heated in an oil bath at 70° C. and magnetically stirred at 500 rpm for 2 h to completely dissolve the polyvinyl alcohol in the deionized water phase to prepare a polyvinyl alcohol solution with a mass-volume concentration of 50 g / L.

[0033] S3, preparing polyethyleneimine composite slurry:

[0034] Multi-walled carbon nanotubes and a sepiolite dispersion are mixed to form a carbon nanotube and sepiolite fiber mixture 1 having a mass-volume concentration of 15 g / L. The mixture 1 is subjected to ultrasonic dispersion treatment to uniformly disperse the carbon nanomaterial therein. A high molecular weight polymer solution is added to the mixture 1, such that the mass of the polymer in the polymer solution accounts for 10 wt % of the solid content of the carbon material and clay mixture, to obtain a carbon material-clay polymer mixed dispersion 2. A polyethyleneimine solution having a concentration of 100 g / L is added to the mixed dispersion 2, such that the mass of the polyethyleneimine in the polyethyleneimine solution accounts for 10 wt % of the solid content of the mixed dispersion 2. The carbon material-clay polymer mixed solution 2 is magnetically stirred at 300 rpm for 10 minutes and subjected to bath ultrasonic treatment for 10 minutes to obtain a uniformly mixed polyethyleneimine composite slurry 3.

[0035] S4, heating assisted evaporation film forming:

[0036] The polyethyleneimine composite slurry obtained in step S3 is poured into a container and assisted evaporated at 40° C. for 6 hours to obtain a clay-based electrothermal composite membrane for directly capturing CO 2 in the air.

[0037] It was determined that the CO2 adsorption performance of the clay-based composite membrane obtained in Example 1 was 1.52 mmol / g, the thermal equilibrium temperature was 105°C after applying a voltage of 30V at both ends of the composite membrane, and the thermal equilibrium temperature under one sunlight was 82°C. Both can achieve regeneration and desorption of the adsorbent, reducing the regeneration energy consumption. After 5 regeneration cycles, the adsorption performance of the composite membrane did not change significantly.

[0038] Example 2:

[0039] A method for preparing a clay-based electrothermal composite membrane for directly capturing CO2 in the air comprises the following steps:

[0040] S1. Preparation of sepiolite nanofiber dispersion:

[0041] Mixing sepiolite with deionized water to prepare a mixed aqueous solution with a mass-volume concentration of 10 g / L to obtain a one-dimensional clay mixed solution; subjecting the one-dimensional clay mixed solution to ultrasonic dispersion treatment to obtain a one-dimensional clay nanofiber dispersion;

[0042] S2, preparing polyvinyl alcohol solution, comprising the following steps:

[0043] The high molecular weight polymer was mixed with deionized water, and the mixture was heated in an oil bath at 70° C. and magnetically stirred at 500 rpm for 2 h to completely dissolve the polyvinyl alcohol in the deionized water phase to prepare a polyvinyl alcohol solution with a mass-volume concentration of 50 g / L.

[0044] S3, preparing polyethyleneimine composite slurry:

[0045] Multi-walled carbon nanotubes and a sepiolite dispersion are mixed to form a carbon nanotube and sepiolite fiber mixture 1 having a mass-volume concentration of 15 g / L. The mixture 1 is subjected to ultrasonic dispersion treatment to uniformly disperse the carbon nanomaterial therein. A high molecular weight polymer solution is added to the mixture 1, such that the mass of the polymer in the polymer solution accounts for 10 wt % of the solid content of the carbon material and clay mixture, to obtain a carbon material-clay polymer mixed dispersion 2. A polyethyleneimine solution having a concentration of 100 g / L is added to the mixed dispersion 2, such that the mass of the polyethyleneimine in the polyethyleneimine solution accounts for 30 wt % of the solid content of the mixed dispersion 2. The carbon material-clay polymer mixed solution 2 is magnetically stirred at 300 rpm for 10 minutes and subjected to bath ultrasonic treatment for 10 minutes to obtain a uniformly mixed polyethyleneimine composite slurry 3.

[0046] S4, heating assisted evaporation film forming:

[0047] The polyethyleneimine composite slurry obtained in step S3 is poured into a container and assisted evaporated at a temperature of 50° C. for 6 hours to obtain a clay-based electrothermal composite membrane for directly capturing CO 2 in the air.

[0048] It was determined that the CO2 adsorption performance of the clay-based composite membrane obtained in Example 2 was 2.05 mmol / g, the thermal equilibrium temperature was 110°C after applying a voltage of 30V at both ends of the composite membrane, and the thermal equilibrium temperature under sunlight was 85°C. Both can achieve regeneration and desorption of the adsorbent, reducing the regeneration energy consumption. After 5 regeneration cycles, the adsorption performance of the composite membrane did not change significantly.

[0049] Example 3:

[0050] A method for preparing a clay-based electrothermal composite membrane for directly capturing CO2 in the air comprises the following steps:

[0051] S1. Preparation of sepiolite nanofiber dispersion:

[0052] Mixing sepiolite with deionized water to prepare a mixed aqueous solution with a mass-volume concentration of 10 g / L to obtain a one-dimensional clay mixed solution; subjecting the one-dimensional clay mixed solution to ultrasonic dispersion treatment to obtain a one-dimensional clay nanofiber dispersion;

[0053] S2, preparing polyvinyl alcohol solution, comprising the following steps:

[0054] The high molecular weight polymer was mixed with deionized water, and the mixture was heated in an oil bath at 70° C. and magnetically stirred at 500 rpm for 2 h to completely dissolve the polyvinyl alcohol in the deionized water phase to prepare a polyvinyl alcohol solution with a mass-volume concentration of 50 g / L.

[0055] S3, preparing polyethyleneimine composite slurry:

[0056] Multi-walled carbon nanotubes and a sepiolite dispersion are mixed to form a carbon nanotube and sepiolite fiber mixture 1 having a mass-volume concentration of 15 g / L. The mixture 1 is subjected to ultrasonic dispersion treatment to uniformly disperse the carbon nanomaterial therein. A high molecular weight polymer solution is added to the mixture 1, such that the mass of the polymer in the polymer solution accounts for 10 wt% of the solid content of the carbon material and clay mixture, to obtain a carbon material-clay polymer mixed dispersion 2. A polyethyleneimine solution having a concentration of 100 g / L is added to the mixed dispersion 2, such that the mass of the polyethyleneimine in the polyethyleneimine solution accounts for 40 wt% of the solid content of the mixed dispersion 2. The carbon material-clay polymer mixed solution 2 is magnetically stirred at 300 rpm for 10 minutes and subjected to bath ultrasonic treatment for 10 minutes to obtain a uniformly mixed polyethyleneimine composite slurry 3.

[0057] S4, heating assisted evaporation film forming:

[0058] The polyethyleneimine composite slurry obtained in step S3 is poured into a container and assisted evaporated at a temperature of 60° C. for 6 hours to obtain a clay-based electrothermal composite membrane for directly capturing CO 2 in the air.

[0059] The CO2 adsorption performance of the clay-based composite membrane obtained in Example 3 was determined to be 2.34 mmol / g, the thermal equilibrium temperature was 95°C after applying a voltage of 30V at both ends of the composite membrane, and the thermal equilibrium temperature under sunlight was 90°C, both of which could achieve regeneration and desorption of the adsorbent, reducing the regeneration energy consumption. After 5 regeneration cycles, the adsorption performance of the composite membrane did not change significantly.

[0060] The above is a further detailed description of the present invention in conjunction with specific preferred technical solutions, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a clay-based electrothermal composite membrane for directly capturing CO2 in the air, characterized in that: The following steps are involved: S1. Preparation of one-dimensional clay nanofiber dispersion: The one-dimensional clay material is mixed with deionized water to prepare a mixed aqueous solution with a mass-volume concentration of 10 to 30 g / L to obtain a one-dimensional clay mixed solution; the one-dimensional clay mixed solution is subjected to ultrasonic dispersion treatment to obtain a one-dimensional clay nanofiber dispersion solution; S2. Preparation of polymer solution: The polymer was mixed with deionized water, and the mixture was heated in an oil bath at 70° C. and magnetically stirred at 500 rpm for 2 hours to completely dissolve the polymer in the deionized water to prepare a polymer solution with a mass-volume concentration of 10 to 50 g / L. S3, preparing polyethyleneimine composite slurry: The carbon nanomaterial is mixed with a one-dimensional clay nanofiber dispersion to prepare a carbon material and clay fiber mixed solution 1 having a mass-volume concentration of 15 to 50 g / L, and the mixed solution 1 is then subjected to ultrasonic dispersion treatment to uniformly disperse the carbon nanomaterial in the dispersion; a polymer solution is added to the mixed solution 1, and the mass of the polymer in the polymer solution is 5 to 15 wt% of the solid content in the mixed solution 1 of the carbon material and clay fiber to obtain a carbon material clay polymer mixed dispersion 2; a polyethyleneimine solution with a concentration of 100 g / L is added to the carbon material clay polymer mixed dispersion 2, and the polyethyleneimine in the polyethyleneimine solution is 10 to 50 wt% of the solid content in the carbon material clay polymer mixed dispersion 2; the carbon material clay polymer mixed dispersion 2 after the polyethyleneimine is added is magnetically stirred at a speed of 300 rpm for 10 minutes and subjected to bath ultrasonication for 10 minutes to obtain a uniformly mixed polyethyleneimine composite slurry; S4, heating assisted evaporation film forming: The polyethyleneimine composite slurry obtained in step S3 is assisted to evaporate at a temperature of 40° C. to 60° C. for 6 to 12 hours to obtain a clay-based electrothermal composite membrane for directly capturing CO 2 in the air.

2. The preparation method according to claim 1, characterized in that The ultrasonic dispersion treatment adopts tip ultrasonic treatment; in step S1, the ultrasonic treatment time is 30 to 60 minutes; in step S3, the ultrasonic treatment time is 10 to 30 minutes.

3. The preparation method according to claim 1, characterized in that The one-dimensional clay material is sepiolite or palygorskite.

4. The preparation method according to claim 1, characterized in that The carbon material is multi-walled carbon nanotubes, carbon black or graphite powder.

5. The preparation method according to claim 1, characterized in that The high molecular polymer solution is a polyvinyl alcohol solution, a chitosan solution, a gelatin solution or a xanthan gum solution.

6. A clay-based composite membrane for directly capturing carbon dioxide from the air, prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of the clay-based electrothermal composite membrane for directly capturing carbon dioxide from the air as claimed in claim 6 in carbon dioxide adsorption.